Patent Document 1 describes one example of a conventional oil free screw compressor. In this conventional one, cooling devices such as air-cooled heat exchangers (an inter cooler, an after cooler, an oil cooler, etc.) are arranged on a back surface of a compressor main body or driving system devices (a motor, a gear casing, etc.). The coolers forming the cooling devices are so arranged as to be exposed to a back surface of the package to take outside air at low temperature directly into the coolers, thereby achieving downsizing of the coolers.
Moreover, in a conventional art described in Patent Document 2, air-cooled heat exchangers (an inter cooler, an after cooler, an oil cooler, etc.) are arranged on one side isolated from a compressor main body and driving system devices inside a package.